1. Field of the Invention
The present invention relates generally to an apparatus for winding dynamoelectric machine field windings and, more particularly, to such an apparatus including a mechanism for preventing the field windings from moving out of a desired position on a stator during a winding operation.
2. Related Prior Art
Stator coil winding, machines are well known that use a moving wire dispensing element for dispensing wire into stator core slots from end to end of the stator core, passing over the end of the core and to an appropriate return slot, returning axially to the opposite core end, and continuing this motion until the coil is completed. One recognized shortcoming of such winding operations is the tendency of the wire forming the coil to move out of the slots of the stator core radially inwardly toward the interior of the stator core, such as may result from tension applied to the wire as the dispensing element is moved between the stator core ends to position the wire in a slot, which may interfere with the proper performance of the winding operation, result in misformed coils, as well as reduced slot fill.
The prior art has proposed various mechanisms for overcoming the problem associated with movement of the wire windings during the winding operation. For example. U.S. Pat. No. 3,414,204 to Friedrich discloses providing wire guiding fingers located adjacent end faces of a stator being wound. In operation, wire is wound over the fingers whereby the wire is held in a desired position as the stator is being wound.
In an alternative approach, shroud members are provided on either end of a stator wherein the shroud members define guiding surfaces for guiding wire into the stator core slots and for preventing the wire from falling to the interior of the stator core, such as is disclosed in U.S. Pat. No. 3,648,938 to Dryburgh.
U.S. Pat. No. 4,498,636 to Boesewetter discloses a further approach to maintaining the field windings within the stator core slot wherein a cylindrical winding tool is formed to closely fit within the interior of the stator core and includes opposing ends extending beyond the ends of the stator core such that the winding tool effectively closes off the slot openings to prevent wire from exiting into the interior of the stator core during the winding operation. However, this approach does not control movement of wire in the stator core slots to prevent displacement toward the central portion of the stator which can result in reduced slot fill.
Accordingly, in spite of the above described mechanisms for improving the operation of forming dynamoelectric field windings, there is a continuing need for a simple and effective mechanism for maintaining the field windings immovably in place on the stator core during the winding operation.